Battery control devices are used, for example, for electric and hybrid vehicles in order to be able to monitor and control high-voltage battery systems which usually comprise a multiplicity of battery cells. For this purpose, a central first electronic unit may be constructed as battery management unit (BMU) which particularly monitors the overall status of the battery system and controls, for example, a charge balance between the battery cells. In addition, local cell supervisory controllers (CSC) are frequently used as second electronic units which, for example, detect states such as cell voltage and temperature for each individual battery cell or for groups of battery cells and communicate these to the battery management unit. The ground potentials of the cell supervisory controllers may be connected to the battery system in this case. The communication link between the battery management unit and the cell supervisory controllers is usually constructed as Controller Area Network (CAN) bus link since this type of link ensures reliable communication also for relatively long communication paths. However, the use of a CAN bus requires complex transmitting/receiving devices for implementing the protocol both in the battery management unit and the cell supervisory controllers.
As a communication link between electronic units, the Serial Peripheral Interface (SPI) bus is also known which may be implemented with less expenditure but is not very suitable for connecting electronic units which are farther apart spatially since an SPI bus link is susceptible to interference signals such as common-mode interference, in particular.
A battery monitoring and control device is known from DE 10 2010 016 175 A1, wherein a primary and a secondary connecting link are provided between a system controller and a battery monitoring module. The primary connecting link may be formed by an SPI connecting link. In the case of a failure or reduction of the serial link, the secondary connecting link, which is constructed as a UART (Universal Asynchronous Receiver/Transmitter) connecting link, handles the communication task.
From U.S. Patent Publication No. 2010/173180 A1, a battery management system is known having a battery which comprises a number of cells and having a number of devices for detecting the statuses of the cells which are coupled to the battery and having a control unit which is connected to a first one of the devices. The control unit may communicate with a destination device via a standard path and via a substitute path.
A battery management device is also known from U.S. Pat. No. 5,850,351 A, in which a number of batteries is monitored by a number of battery monitoring modules, one battery monitoring module being allocated to each battery.
From U.S. Patent Publication No. 2007/182377 A1, finally, a monitoring system is known for monitoring the voltage of a number of batteries, each battery comprising a number of cells. To each battery, a monitoring unit is allocated. In this arrangement, a first and a second monitoring unit measure the same cell of a battery. The monitoring units are arranged in a chain, adjacent monitoring units being connected via communication interfaces.